0.5.1 (2012-12-25)

implemented css lint based CSSLintChecker as a working replacement for
CSSChecker. The CSSLIntChecker requires a working java installation and is
based on the included js.jar and csslint-rhino.js jar file.

skip CSSChecker by default. This chcker produces unuseable output for
the twitter bootstrap styles sheets. Every second style is reported as
unknown.